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-   -   high rpm/boost issue? (https://www.miataturbo.net/general-miata-chat-9/high-rpm-boost-issue-13591/)

nicacus 10-24-2007 03:10 PM

high rpm/boost issue?
 
I have searched and found nothing.
not really sure where to post this... since this isn't a Greddy or DIY.

As usual my car revs and idles perfectly normal, first gear at WOT has no issues until about 6000 RPM then comes the problem.
my car will bog like it is starving for air, in second the same problem comes only sooner, at about 5000 RPM and it comes progressively sooner the higher gear you are in, on the freeway in 5th it happens anytime you go half throttle or more. It isnt as bad if you stay out of boost and speed up slowly but it will still happen at about 6K in any gear. At first the A/F ratio would go nutso rich down to 11:1 sometimes 10:1. I adjusted it back to 12:1 with the voodoo box, but it still happens.

Boost is set to about 5.5 PSI

Retarded the timing to 6 degrees
The turbo makes a funny noise when it happens... it makes it's spooling sound but it sounds like it intermittent. for example if the line were the spooling noise
Normal:
------------------------------------
Problem:
------------ ------- -------- ------ - - - - - -
Like it is cutting out...

that’s probably a shitty way to describe it...

Could it be a boost leak??

I'd ask FM but they usually take 3 days to reply..

Ben 10-24-2007 03:12 PM

clutch

cjernigan 10-24-2007 03:13 PM

Call FM, emailing is pointless if you want an answer.
You might have leak at your BOV, what kind is it and is it recirced or VTA. Otherwise bogging is usually a symptom of going lean. You do have a wideband right?

cjernigan 10-24-2007 03:14 PM


Originally Posted by Ben (Post 166730)
clutch

lol I forget about that one, figure that would be pretty apparent to most people.

nicacus 10-24-2007 03:20 PM

It isnt the clutch slipping..
it a GFB blow off valve, recirculated, not leaking.
it doesnt go lean at all.
and I do have a wideband

patsmx5 10-24-2007 03:25 PM

Try putting in new plugs.

nicacus 10-24-2007 04:39 PM

if it were the clutch slipping wouldnt it slip and keep slipping?? not slip then grab then slip... etc.. ??
the plugs are almost brand new.. I changed them about a week before I put the turbo in, so less than trhee months ago. they are NGK iridium IX

magnamx-5 10-24-2007 09:36 PM

It is a cheap check to swap them out. Also check the coil grounds.

Braineack 10-24-2007 09:56 PM

what are they gapped at?

neogenesis2004 10-24-2007 10:14 PM

Sounds exactly like what I would have described when my clutch was giving out. its worse in higher gears because there is more load. Progressive throttle doesn't make it slip because there is no tq burst but its gonna let out eventually because it can't hold the tq.

Ben 10-24-2007 10:15 PM


Originally Posted by nicacus (Post 166783)
if it were the clutch slipping wouldnt it slip and keep slipping?? not slip then grab then slip... etc.. ??
the plugs are almost brand new.. I changed them about a week before I put the turbo in, so less than trhee months ago. they are NGK iridium IX

Boost is dependent on load. Slippy cluch = less load = less boost = clutch cools and grabs = more boost = clutch slips

break up with load usually indicates ignition grief, typically plugs or wires, but your description sounds more like clutch to me.

nicacus 10-25-2007 11:26 AM

If I had to take a shot in the dark at what detonation felt like I would say that’s the best way to describe what it feels like.
I have had my clutch slip before this is a totally different feeling. It isn’t a gradual not wanting to go feeling, it's a sudden hesitation like you would get if you were teaching someone how to drive a stick and they were trying to start in third gear.

I'm not sure what the plugs are gapped at.. I don’t think the gap was ever changed from when I bought them. I will pull them tonight after work and check them out.

nicacus 10-26-2007 02:57 AM

the NGKs were gapped at like 45
I bought some cheapo autolites that are for the 323 GTX and gapped them at 35
problem solved...

again I feel like an ass..

Thanks for the advice

cjernigan 10-26-2007 07:26 AM

Switch to COPs and you can run .40 gap.

Braineack 10-26-2007 08:35 AM


Originally Posted by Braineack (Post 166916)
what are they gapped at?


what a smart post!


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